This invention is related to wireless devices, and in particular to providing programmable performance and power characteristics in complementary metal oxide semiconductor (CMOS) integrated circuits for radio applications in order to reduce power consumption and increase yield.
Integrated circuit devices are omnipresent nowadays and used for both analog and digital functions, often on the same device. Metal oxide semiconductor (MOS) technology, in particular CMOS technology is well established for digital applications and offers many advantages over other technologies.
As is common, the term integrated circuit, IC, and chip shall be used throughout this specification to refer to an integrated circuit.
The use of CMOS in analog circuits, e.g., high frequency radio circuits has been limited for many reasons. One reason is the difficulty in realizing accurate circuits using CMOS technology. Another problem has been the low yields obtainable from devices operating near the high frequency limits of the process. Another has been process variation of the CMOS process. Another has been transistor behavior with temperature. It would be advantageous to have a CMOS chip that is tunable so that more chips are usable for a given CMOS process. It would be advantageous to have a CMOS chip that is tunable to account for the variation of transistor behavior with temperature.
Different radio applications require a different level of performance, and different levels of performance result in different power consumption. Some applications may require very low levels of power consumption, while in other applications, the performance is paramount. Traditionally, a chip vendor may design and offer different chips for these different applications: a low power chip for low power applications, and a high performance chip for high performance applications. It would be advantageous to have a single chip that can be used for both low power and high performance applications. Using the same chip would allow economies of scale to lower the cost of each chip.
Thus there is a need for a CMOS radio chip that is tunable so that more chips are usable for a given CMOS process. There further is a need for a CMOS radio chip that is tunable to account for the variation of transistor behavior with temperature.
One wireless application that is becoming more widespread is that of wireless local area networks (WLANs). IEEE 802.11 is a standard for wireless local area networks, and IEEE 802.11a is a WLAN standard for communicating in the 5 GHz region. There thus is a need for inexpensive radio chips suitable for use with IEEE 802.11a. For more information on the IEEE 802.11 and IEEE 802.11 a standards, see: ANSI/IEEE Std 802.11, 1999 Edition (ISO/IEC 8802-11:1999) Local and metropolitan area networks—Specific Requirements—Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, and IEEE Std 802.11a-1999[ISO/IEC 8802-11:1999/Amd 1:2000(E)](Supplement to IEEE Std 802.11, 1999 Edition) Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: High-speed Physical Layer in the 5 GHz Band. The standards are available on the Internet at several locations, including from the IEEE (www.IEEE.org) and in particular at http://grouper.ieee.org/groups/802/11/index.html.